1. Field of the Invention
The present invention relates generally to electrolytic pumps for electrochemical fluids. More particularly, the present invention relates to an electrolytic pump which is adapted for use in an in-tank plating bath electrochemical sensor. The pump is designed to provide an adjustable constant flow of electrochemical fluid through the sensor, such flow being of the type which is required for optimal measurement and analysis of the electrochemical properties of the fluid.
2. Description of Related Art
Pump requirements for circulating fluids through the sensors used in plating bath analysis methods, such as the method disclosed in U.S. Pat. No. 4,631,116, which is assigned to the present common assignee, are typically met by using an externally mounted or submerged mechanical pump which is connected to the sensor via a network of tubing (see col.6, lines 2414 29). Alternatively, a "fish tank" type of pump requiring tubing, an air supply, and an air metering device could be used.
As was noted in U.S. Pat. No. 4,631,116, agitation of the electrolytic solution at the sensor creates turbulent conditions which decrease the sensitivity of the analysis method and its ability to resolve fine structure (see col.15, lines 17-18). In response to this problem, in-tank electrochemical sensors have been developed in which the sensor measurement electrodes are housed in a tube which is submerged within the plating solution. The solution could thus be drawn past the sensors at specified flow rates, and experimentation with the sensors has shown that using a medium flow rate optimized the performance of the electrochemical fluid analysis system. This optimal flow rate is maintained by the pump.
However, the current pumping methods described above are expensive and typically require frequent and costly maintenance. The tubing must be replaced quite often, and the pump itself is vulnerable to breakdown. Production costs associated with the use of in-tank sensors are thus significantly higher as a result of the limitations inherent in the currently available pumping techniques.
In addition, the currently utilized pumps consume considerable amounts of power in the course of continuous operation of a plating bath analysis system. This contributes to higher energy costs and resultant higher production costs.
Furthermore, the current external or submerged mounting of the pump and the required tubing is awkward and complicates the equipment associated with the plating bath setup. In the case of the externally mounted pump, this extra equipment is visually unappealing and represents a potential hazard to those working in and around the plating area.
As is apparent from the above, there presently is a need for a rugged, inexpensive, low maintenance and limited power consumption electrolytic pump. Further, the pump should require no external or submerged motor or tubing. The pump should include all of these features and still be able to draw fluid through the body of the electrochemical sensor at the desired optimal flow rates.